1. Field of the Invention
The present invention relates to a polyurethane foam and a polishing pad using the same.
2. Description of the Related Art
With a semiconductor substrate, such as a silicon wafer, an optical member, such as a lens, or an electronic material, such as a magnetic head, hard disk, a high precision is required of the product, and polishing and smoothening of a surface are essential in the manufacturing process. An apparatus for performing the polishing is generally arranged from a polishing head that holds a polishing object, a polishing pad for performing a polishing process on the polishing object, and a polishing platen for holding the polishing pad. Then, while using a polishing slurry made of a polishing agent and a chemical, the polishing object and the polishing pad are made to undergo relative movement to remove projections and uneven portions on the polishing object surface and thereby smoothen the polishing object. The polishing pad used in this process is required to have a high hardness and a high elasticity as characteristics for preventing generation of defects in the product.
A polyurethane foam, which, in order to meet the above required characteristics, uses a urethane composition prepared by blending a prepolymer, obtained by reacting tolylene diisocyanate (TDI) as a polyisocyanate and polytetramethylene ether glycol (PTMG) as a polyol, with 3,3′-dichloro-4,4′-diaminodiphenylmethane (MOCA) as a curing agent, foamed particles, air, water, etc., and is manufactured by making the urethane composition foam and chain-extending the prepolymer, and a polishing pad using the foam have been disclosed from before (see Patent Documents 1 and 2).    Patent Document 1: Japanese Published Unexamined Patent Application No. 2000-178374    Patent Document 2: Patent Publication No. 3685064